Manage your subscription

2008: The year in the solar system

By Rachel Courtland and Maggie McKee

The solar system came into unprecedented focus in 2008. Various spacecraft revealed previously unseen swathes of Mercury, found a ring around one of Saturn’s moons, and landed squarely on a patch of Martian ice.

Dust storms

Not to be outdone, the Mars Reconnaissance Orbiter found what may be vast underground ice glaciers near the equator as well as widespread opal deposits, suggesting liquid water persisted for longer on the planet than previously suspected. The probe also found rock outcrops containing carbonates, suggesting the water that formed them about 3.5 billion years ago might have been less acidic and more hospitable to life than originally thought.

Advertisement

The news was less positive for NASA’s Mars Science Laboratory. The SUV-sized, nuclear-powered rover has unresolved technical problems that will force it to launch in 2011, two years later than planned. The delay will add &dollar;400 million to the mission and could force NASA to postpone another major planetary mission.

Meanwhile, the twin Mars rovers have refused to die after five years on the Red Planet, although a dust storm caused Spirit’s power levels to drop to an all-time low in November.

Cassini also made three flybys of Saturn’s moon Enceladus to taste and image giant plumes of water vapour and ice that extend hundreds of kilometres from the moon’s surface. The energy source for these plumes is still being debated, but high-speed jets within the plume may point to a reservoir of liquid water – which might be hospitable to life – beneath the surface.

The Deep Impact spacecraft, which sent a probe crashing into a comet in 2005 and is now searching for extrasolar planets, was used in the first test of an interplanetary internet that could streamline the way data is sent between spacecraft and Earth. The probe also imaged Earth from 50 million km away, revealing what alien astronomers with telescopes far more powerful than our own might see when they look at our home planet.

Celestial spectacle

Back on Earth, astronomers continued to debate whether Pluto should be considered a planet. The International Astronomical Union (IAU), which demoted Pluto to ‘dwarf planet’ status in 2006, said Pluto and objects like it should be called ‘plutoids’, a term one astronomer said sounded like ‘hemorrhoids’.

Other notable sky events in 2008 included a rare conjunction of Venus, Jupiter and the Moon, a full Moon that shone about 30% brighter in December than at other times in the year because the Moon was about as close as it ever comes to Earth, and a ‘fireball’ that not only lit up the skies above Canada but also left behind dozens of fresh meteorites that scientists and meteorite hunters rushed to recover.